Candles have been known for many centuries going back to the eighth century B.C. The nature of candles is described in Ullmann's Encyclopedia of Industrial Chemistry, Volume A5 at pages 29-30 where it is seen that candles are made from paraffin, beeswax and stearin as basic materials, and where a host of additives may also be present.
It is not surprising that with candles and wax becoming increasingly more important attention was paid as to how to stabilize the said materials. At the National Candle Association Meeting in Houston, 1994, R. van der Vennet presented a paper on “Antioxidants in Wax—Replacement of BHT” touting the use of Vitamin E (tocopherol) as an antioxidant to prevent the yellowing of wax when oxidized. WO 94/13736 describes the same invention.
EP 359,488 A3 and EP 133,964 B1 describe stabilized waxes used in cosmetics where the waxes are the same or similar to those used in candles.
EP 5,922 A1 describes lip cosmetics where the waxes are useful in lipsticks and are related to those useful in candles.
U.S. Pat. No. 5,879,694 describes in detail transparent gel candles both in composition and structure. The use of BHT as an antioxidant is mentioned.
At the National Candle Association Technical Meeting on Apr. 16, 1998, F. A. Ballentine et al., presented a paper entitled “Inhibiting Color Fading of Dyed Candles with CYASORB® Light Absorbers” in which the general theories of thermal oxidation and photodegradation are discussed along with data on the effect of light absorbers on color stability of dyed candle waxes. The light absorbers compared are 4-octyloxy-2-hydroxybenzophenone UV-531; 4-methoxy-2-hydroxybenzophenone UV-9; 2-(2-hydroxy-5-methylphenyl)-2H-benzotriazole UV-5365; 2-(2-hydroxy-5-tert-octylphenyl-2H-benzotriazole UV-5411 and 2-(2-hydroxy-3,5-di-tert-amylphenyl)-2H-benzotriazole UV-2337).
U.S. Pat. No. 5,964,905 teaches dyed and scented candle gels containing triblock copolymers and a hydrocarbon oil of high flash point. This reference teaches that a light (UV) absorber may be used to improve the shelf stability of the candle color when exposed to visible or ultraviolet light. Two preferred absorbers are ethylhexyl p-methoxycinnamate (PARSOL® MCX, Roche) and 2-(2-hydroxy-5-tert-octylphenyl)-2H-benzotriazole (CYASORB® 5411, Cytec).
WO 00/22037 teaches the stabilization of solid, shaped and colored wax articles, including candles, using a malonate UV absorber which may optionally contain a hindered amine moiety as part of the malonate compound structure. The wax articles are dyed with a variety of oil soluble dyes and pigments. The samples protected by dimethyl p-methoxy-benzylidinemalonate exhibited better resistance to discoloration that did samples stabilized with selected benzotriazole or benzophenone UV absorbers.
Japanese Hei 3-278554 teaches that wax crayons (drawing materials) colored by organic pigments can be stabilized by a hindered amine and/or benzotriazole.
In respect to wax stabilization, the use of selected hindered amines and/or benzotriazole UV absorbers is also known in the prior art as seen in U.S. Pat. Nos. 3,530,084; 4,379,721; 4,616,051 and 5,964,905 and copending application Ser. Nos. 09/495,495, 09/495,496 and 09/741,583.
Selected compounds which contain both a hindered amine moiety and a benzotriazole moiety in the same molecule are described in U.S. Pat. Nos. 4,289,686 and 5,021,478.
U.S. Pat. Nos. 4,314,933; 4,481,315; 5,278,310; 5,382,588 and 6,166,218; and WO 99/23093 describe other benzotriazole UV absorbers which are related to the instant compounds.
N. Lin et al., Poly. Deg. Stab. 67, 307 (2000) and J. Zakrzewski et al., Poly Deg. Stab. 65, 425 (1999) and ibid, 67, 299 (2000) describe the stabilization of substrates using benzotriazole UV absorbers.
EP 704,560 A1 describes the stabilization of pigmented fibers with a synergistic mixture of hindered amine and UV absorber such as a benzotriazole or s-triazine.
The instant compounds are novel materials and their utility as light stabilizers for thermoset and thermoplastic compositions, for photographic applications and for candle wax is unknown.